Rotary joints are commonly employed with drying and cooling drums widely used in the paper manufacturing art, and related manufacturing processes, wherein an elongated web succesively engages steam-heated or water-cooled drums for treating the web. Such rotary joints include relatively stationary components communicating with fluid supply or exhaust and drain systems, and rotating components associated with the drum. The joints use a variety of seal arrangements to establish a sealed relationship between the rotating and stationary components, and various mounting arrangements are used with rotary joints to compensate for eccentricity in drum rotation, ease of installation and maintenance, economy of manufacture, thermal expansion, seal wear, etc. The most common mounting for rotary joints used with heat exchanging drums include nonrigid joint body supports which permit a limited movement or adjustment of the joint body relative to the drum journal and wherein limited eccentricity and thermal expansion conditions may be accomplished.
In certain types of applications and installations of rotary heat exchanging drums it is known to directly mount a rotary joint seal in a fixed relationship to the drum journal or shaft. While this type of installation does create some problems, it has the advantage of permitting the rotary joint to be more compact in size as compared with a conventionally supported joint, misalignment problems are minimized, and fewer wearing parts are required. In such an installation, journal-supported components are affixed to the end of the drum journal and include a seal which is fixed with respect to the journal and concentric to its axis of rotation. The joint body is fixed with respect to the journal bearing support structure and includes a seal engaging with the journal supported seal to establish a relatively rotating, but fluid-tight, relationship between the journal and the joint body. A supply or drain conduit communicates with the body for supplying or receiving the fluid passing through the joint and drum. Springs are usually employed in the joint body to bias the body-mounted seal into engagement with the journal seal.
Known journal-mounted rotary joints of the aforedescribed type are commercially available, but problems exist with such known joints, and it is an object of the invention to provide a journal-mounted rotary joint for rotating heat exchanging drums wherein the joint includes unique components and the parts of the joint are economical to manufacture and readily replaceable for service and maintenance purposes.
Another object of the invention is to provide a journal-mounted rotary joint for heat exchanger drums wherein the joint includes a seal having differential area pressure faces wherein the forces imposed upon the seal by the internal fluid pressure are substantially balanced which produces less pressure at the seal contact surfaces to increase the seal life and lower the operating torque of the joint.
Yet another object of the invention is to provide a journal-mounted rotary joint for heat exchanger drums wherein the journal-mounted seal and the joint body mounted seal are located within adapters and seal plates, respectively, which may be readily removed from their associated structure to facilitate repair and replacement.
An additional object of the invention is to provide a journal-mounted rotary joint for heat exchanger drums wherein springs are employed to bias the joint body mounted seal toward the journal-mounted seal, and the springs are isolated from contact with the fluid medium within the joint reducing deleterious effects on the springs.
In the practice of the invention, an annular flange is mounted upon the end of the journal (shaft) of a rotating heat exchanger drum by a set of bolts received within threaded holes defined in the end of the journal. An annular adapter plate is removably bolted to the flange and includes an annular seal coaxial with the journal axis and bore and having a radial sealing face.
The rotary joint body is adjustably mounted in a fixed position upon the journal support structure adjacent the journal wherein the body will be stationary and may be accurately aligned with the journal axis. The body includes an internal chamber which communicates with a body port or conduit which may be attached to a supply for steam or hot or cold water, or the fitting may communicate with a drain system if the joint is employed with the discharge side of the drum.
A radially oriented seal plate is bolted to the joint body and includes an internal cylindrical bore concentric to the journal axis which receives the cylindrical portion of a carbon seal supported in the seal plate. An O-ring is located between the carbon seal and the seal plate bore, and the carbon seal is capable of axial movement within the seal plate bore. Radial pressure surfaces are defined at each axial end of the carbon seal and the area of the surface which imposes an axial force on the seal toward the journal mounted seal is slightly greater than the differential pressure area imposing a force on the carbon seal in the opposite direction. Thus, the fluid pressure within the joint aids in maintaining the two seals in engagement, but the force with which the seals engage is controlled to extend the seal life and lower the operating torque.
A plurality of compression springs are mounted in blind holes defined in the seal plate about its bore, and these compression springs engage a radial flange defined upon the carbon seal imposing a force on the carbon seal to insure engagement of the seal surfaces prior to the presence of a pressurized medium within the joint body. As the compression springs are isolated from the body chamber, and the fluid passing through the joint, the springs are not subjected to corrosion and adverse effects arising from fluid contact.
The joint of the invention is so constructed that metal-to-metal contact of relatively moving parts does not occur, and the adapter and seal plate may be readily removed from their supporting components for replacement and service.